The BDS is a global navigation satellite system autonomously developed and independently operated by China. The Chinese BDS, the American Global Positioning System (GPS), the Russian Global Navigation Satellite System (GLONASS), and the European Galileo Systems are the four core navigation satellite systems approved by the International Civil Aviation Organization (ICAO), and strive to provide high-quality navigation, positioning, and time services to users all over the world.
BDS positioning is inevitably susceptible to various errors such as ionospheric delay, troposphere delay, and multipath. Therefore, before precision positioning of the BeiDou system is implemented, it is necessary to perform a quality test and analysis of observation data from the BeiDou system, so as to mitigate and eliminate the impact of various error factors on positioning results.
To improve the overall service quality regarding precision and integrity of a navigation satellite system, the ICAO proposes the concept of a Ground-Based Augmentation System (GBAS). Under the construction of ground reference stations with known locations, GBAS not only improves the precision of satellite navigation, but also adds a series of integrity monitoring algorithms to improve indicators of system integrity, availability, and continuity, so as to provide reliable observation data and related service information to BDS users. Therefore, an airplane equipped with corresponding on-board equipments in the coverage zone of an airport obtains high-standard precision approach and landing guidance services. Regional augmentation systems such as the Ground-based Regional Integrity Monitoring System (GRIMS) for China's GNSS, the International GNSS Monitoring & Assessment System (iGMAS), the International GNSS Service (IGS), and the BeiDou Continuously Operating Reference Stations (CORS) are particularly applied to the GBAS.
However, for observation data from BeiDou satellites that is provided by the GBAS, the impact of problems that may exist in the observation data itself on data quality is often ignored. The most notable one is the correlation of the observation data, for example, channel correlation that exists when double satellites separately encounter failures, and the correlation of adjacent epochs when a single satellite encounters two failures at the same time. If an alarm fails to be raised in time for a failure that causes correlation, the observation data is affected, and reliable satellite status information cannot be provided. In this case, the safety of all users in the BDS is endangered, and the social safety and life safety are greatly jeopardized.
Therefore, to resolve the foregoing problems, a processing method based on observation data from the BDS is needed, where the processing method can perform correlation analysis of observation data from BeiDou satellites that is provided by a GBAS and improve the data quality and the service level of the BDS.